The subject matter of the present invention pertains to well bore apparatus, and more particularly, to a dual action valve for use in the well bore apparatus including at least two pressure responsive members.
Well bore apparatus for use in conjunction with oil exploration typically includes perforating apparatus and drill stem testing apparatus. The perforating apparatus includes perforating guns for perforating a formation in a borehole and the drill stem testing apparatus including two valves and at least two mechanisms, one mechanism for opening one valve and another mechanism for closing the other valve. When the perforating gun perforates the formation, and the well fluids begin to flow, it is necessary to open a valve to permit the well fluids to flow to the well surface. Therefore, the first mechanism opens the first valve. The pressure associated with a flow of the well fluids to the surface, termed "flow pressure", is measured. The first valve must remain open, since there is no way to close the first valve. However, a further pressure test, termed a "shut in test", must yet be performed, this test requiring a closed valve. Therefore, the second mechanism closes the second valve. When the second valve is closed, the increase in pressure of the well fluids at the second valve, termed the "shut in pressure", indicative of the formation pressure, is measured. However, the apparatus required to measure the flow pressure and the shut in pressure of the well fluids included at least two tools, a first tool including the first mechanism and the first valve, and a second tool including the second mechanism and the second valve. The first mechanism in the first tool opened the first valve to measure the flow pressure, and the second mechanism in the second tool closed the second valve to measure the shut in pressure. The first and second mechanisms each include a -rupture disc. A first rupture disc in the first tool was set to rupture when a first predetermined annulus pressure was exceeded, and a second rupture disc in the second tool was set to rupture when a second predetermined annulus pressure was exceeded. Since each tool possessed only one rupture disc, it was required that the tool be run into the well bore or borehole with its valve being either initially open or initially closed. When a pressure test required both an initially open and an initially closed valve (e.g., to sequentially measure flow pressure and shut in pressure), two tools were run into the borehole, one tool having the initially closed valve with a rupture disc set to rupture in response to a first predetermined annulus pressure, and another tool having the initially open valve with a rupture disc set to rupture in response to a second predetermined annulus pressure Other systems included a different mechanism for opening and closing a valve. In these systems, one valve, associated with one tool, is opened or closed, selectively. However, rupture discs were not used. Instead, annulus pressure is increased, which pressure is applied against one surface of a piston, the other surface of the piston being subject to another pressure which is a result of a contact with a liquid or gas disposed within a cavity. When the annulus pressure is increased to a point where a pressure force on the one surface of the piston exceeds the pressure force on the other surface of the piston, the piston moves in a direction which may open the valve; when the annulus pressure is reduced, the pressure force on the other surface of the piston moves the piston in an opposite direction thereby closing the valve. If the annulus pressure is accidentally reduced, the valve closes at a time when an open valve is required. In addition, since rupture discs are not utilized, the pressure needed to open the valve is not precisely known; the only way to close the valve involves bleeding off the annulus pressure, whereby the pressure required to close the valve is also not known with any kind of certainty. A system or method is needed to selectively open or close at least one valve in one tool with some measure of precise certainty in regards to the pressure needed to open the valve and the pressure needed to close the valve.